He was of course the original physical Boba Fett (Voiced by Jason Wingreen until 2004's DVD release switched it to Morrison) in ESB and ROTJ (apart from the SEs's added scenes).
He also played the Imperial officer guarding Leia and setting up Vader's trap for Luke in ESB, and Co-Captain Colton of Bail Organa's ship in Revenge of the Sith.
Also had a small recurring role in some of Roger Moore's James Bond films as Smithers, one of Q's assistants, and many other films and TV series.